<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>border-image</title>

    <style>
        :root {
            --url: url('https://s3-us-west-2.amazonaws.com/s.cdpn.io/652/hearts-border-image.png');
        }

        html,
        body {
            width: 100%;
            height: 100%;
            display: flex;
        }

        div {
            position: relative;
            width: 200px;
            height: 120px;
            margin: auto;

        }
        .heart{
            border: 21px solid;

            border-image: var(--url) 21 round;
        }
      
    </style>
</head>

<body>
    <div class="heart"></div>

</body>

</html>